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Tutorial 14

Tutorial 14: Stokes' Theorem

Tutorial QuestionTutorial Solution (Early Access)
  1. Suppose F=y,x,z\mathbf{F}=\langle-y, x, z\rangle and SS is the part of the sphere x2+y2+z2=25x^{2}+y^{2}+z^{2}=25 below the plane z=4\mathrm{z}=4, oriented with the outward-pointing normal (so that the normal at (5,0,0)(5,0,0) is i\mathbf{i} ). Compute the flux integral Scurl F.dS\iint_{S} \text{curl } \mathbf{F} . \mathrm{d} \mathbf{S} using Stokes' theorem.

  2. Use Stokes' theorem to evaluate ScurF.dS\iint_{S} c u r \mid \mathbf{F} . \mathrm{d} \mathbf{S} where F=z2i3xyj+x3y3kF=z^{2} \mathbf{i}-3 x y \mathbf{j}+x^{3} y^{3} \mathbf{k} and S\mathrm{S} is the part of z=5x2y2z=5-x^{2}-y^{2} above the z=1z=1. Assume that SS is oriented upwards.

  3. Use Stokes' theorem to evaluate cF.dr\int_{c} \mathbf{F} . d \mathbf{r} where F=z2i+y2j+xk\mathbf{F}=z^{2} \mathbf{i}+y^{2} \mathbf{j}+x \mathbf{k} and CC is the triangle with vertices (1,0,0),(0,1,0)(1,0,0),(0,1,0) and (0,0,1)(0,0,1) with counter clockwise rotation.

  4. Verify Stokes' Theorem for the field F=x2,2x,z2\boldsymbol{F}=\left\langle x^{2}, 2 x, z^{2}\right\rangle on the ellipse S={(x,y,z):4x2+y24,z=0}S=\left\{(x, y, z): 4 x^{2}+y^{2} \leq 4, z=0\right\}

  5. Verify Stokes' Theorem for F=y2,x,5z\boldsymbol{F}=\left\langle y^{2},-x, 5 z\right\rangle and SS is the paraboloid z=x2+y2z=x^{2}+y^{2} with the circle x2+y2=1x^{2}+y^{2}=1 as its boundary.

  6. Use Stokes' Theorem to calculate (×F)n^dS\iint(\nabla \times \boldsymbol{F}) \cdot \hat{n} d S for F=xz2,x3,cos(xz)\boldsymbol{F}=\left\langle x z^{2}, x^{3}, \cos (x z)\right\rangle where SS is the part of the ellipsoid xx2+y2+3z2=1x x^{2}+y^{2}+3 z^{2}=1 below the xyx y-plane and n^\hat{n} is the lower normal.

  7. Use Stoke's Theorem to evaluate the line integral Fdrc\int \boldsymbol{F} \cdot d \boldsymbol{r} c where F\boldsymbol{F} is the vector F=\boldsymbol{F}= (4ex2y)i+(16sin(y2)+3x)j+(4y2xez)k\left(4 e^{x^{2}}-y\right) \boldsymbol{i}+\left(16 \sin \left(y^{2}\right)+3 x\right) \boldsymbol{j}+\left(4 y-2 x-e^{z}\right) \boldsymbol{k} and CC is the curve of intersection of the cylinder x2+y2=16x^{2}+y^{2}=16 and the plane z=2x+4yz=2 x+4 y and CC is oriented in a counterclockwise direction when viewed from above.

  8. Evaluate the line integral of F(x,y,z)=xy,2z,3y\boldsymbol{F}(x, y, z)=\langle x y, 2 z, 3 y\rangle over the curve CC that is the intersection of the cylinder x2+y2=9x^{2}+y^{2}=9 with the plane x+z=5x+z=5.

  9. Evaluate (×F)ndS\iint(\nabla \times \boldsymbol{F}) \cdot \boldsymbol{n} d S where F(x,y,z)=yz,xz,xy\boldsymbol{F}(x, y, z)=\langle y z, x z, x y\rangle and SS is the part of the sphere x2+y2+z2=4x^{2}+y^{2}+z^{2}=4 that lies inside the cylinder x2+y2=1x^{2}+y^{2}=1 and above the xyx y-plane.